Candies, confectionaries, chewing gum, medicines, crackers, cookies, and small manufactured foods are designed small enough so that one or more may be placed in one's mouth for chewing or dissolving or swallowing whole. Such small objects often bear a marking, such as one or more letters and numbers. For example, a fictitious candy identified by a name beginning with the letter “A” may have a soft inner comestible candy enclosed in a relatively hard and rounded candy shell. On the face of the shell, the manufacturer of the candy may print the letter “A” to distinguish the manufacturer's candy from other candies with similar shapes. In a similar manner, medications may carry indicia to identify the manufacturer of the pill, the medication contained in the pill, or both.
Consumers often make judgments on the value of products based upon the packaging or appearance of the products. A consumer will likely notice the indicia on candy or medication. If the indicia are obscured or reflect broken type, the consumer may form an unsatisfactory opinion about the quality of the product or the competence of the manufacturer. Accordingly, manufacturers pay close attention to carefully printing indicia on their products and discard products with obscured, unclear or broken typeface.
Indicia may be obscured during printing by debris from broken objects or excess ink. For example, in an offset printing process, an engraved roller may have a rigid, engraved pattern of indicia that is transferred first to a blanket roller and then to a candy or medicinal tablet or capsule. During an offset printing process the engraved roller passes through an ink bath to ink indicia that appear as a raised surface on the engraved roller. The inked, engraved roller contacts and transfers its inked images to the blanket roller. The blanket roller is has a soft surface for receiving the inked indicia from the engraved roller and transferring the indicia to the candy or tablets. The candies or tablets are held in pockets of a web or other conveyor and carried past the blanket roller. One face of the candy or tablet is turned toward the blanket roller to receive the inked indicia. Those skilled in the art also refer to the blanket roller as the print roller. In either instance, those skilled in the art are referring to a roller with a pliable surface for receiving inked images from the rigid, inked surface of the engraved roller.
Candies, foods, and medicines may come in any one of a number of three dimensional shapes. The simplest shapes are items with opposite flat surfaces spaced from each other by a uniform thickness, in effect, a flat, cylindrical shape. The top and bottom surfaces normally have the same geometric shape which may be any polygon. Other shapes use opposing surfaces with the same curved surface, including and not limited to circles, ovals, and other multi-curved shapes. Such items may be referred to as pills, tablets, lozenges, troches, or capsules.
There are a number of problems encountered in printing indicia on small objects such as candies or pills. The objects are generally fragile and easily breakable. In the normal course of printing, the pressure of the blanket roller against the objects may crack one or more objects and debris from the cracked objects may adhere to the blanket roller and/or transfer to the engraved roller. Such debris will leave an imperfect imprint on one or more objects. Accordingly, manufacturers often must stop the printing process and have a worker clean the blanket roller and the engraved roller.
Cleaning the rollers requires little or no skill. It is normally a manual activity. In a typical cleaning operation, a worker stops the press and uses brushes and cleaning fluid to scrub the ink and debris from the rollers. The blanket roller requires frequent cleaning. During each cleaning, a worker shuts down the offset printing press and cleans the blanket roller. The engraved roller is cleaned less frequently. The cleaning operations are repetitive and boring. Although cleaning the rollers is very important to appearance of the final product, cleaning is often poorly performed. When cleaning is poor, more candies and medicines are rejected at final inspection, thereby reducing productivity and increasing costs of manufacture.
There are known methods and apparatus for cleaning flexographic printing plates. See, for example, prior U.S. Pat. Nos. 7,011,025 and 8,590,449, which are hereby incorporated by reference for all purposes. However, flexographic printing plates have flexible, raised indicia, rather than the hard indicia made of ceramic or steel that is used to print candies and medicines. Likewise, flexographic printing does not require a blanket roller of pliable material.